384
The shoot height (Fig. 14.5b) of C. balansae Río Seco and C. fissilis Guaraní was
significantly affected under 600 mm with respect to the 1200 mm treatment. A different behavior was observed in C. balansae × C. saltensis hybrid (Pintascayo),
which was not affected by the water deficit, since it presented no significant differences between 600 mm and 1200 mm treatments.
The water balance was more efficient in seedlings from natural environments
with lower rainfall regimes. Besides, the efficiency was also manifested in the water
use, since the provenances from natural drier environments were able to grow more
when the water regime treatment was lower. Differences on drought responses
among tree ecotypes growing in tropical and subtropical rainforests may be attributed to genetic differences in physiological and morphological adaptive responses
(Engelbrecht and Kursar 2003). Plant responses to water deficit, when they are outside their natural environments, depend on the rainfall regimes of their native habitats (Otieno et al. 2005).
In a subsequent trial, all Argentinian species of the genus were compared with
respect to growth traits (Grignola 2014). It included five provenances of C. balansae, two of C. fissilis, two of the hybrids between C. saltensis and C. balansae, two
of C. saltensis, and, since it was not possible to obtain enough seeds of C. angustifolia from the same provenance, a pool of several sources was used to represent this
species. The trial was established on 100 cm
3
individual pots filled with inert substrate and slow-release fertilizer in the greenhouse of Famaillá Experimental Station
(27° 3’ S, 65° 25’ W, 450 m asl), with seeds from trees selected in the natural forest
according to growth, health, and shape criteria. The hybrid character of adult plants
of C. saltensis × C. balansae was confirmed through genetic markers.
Seventy days after germination, the total height and collar diameter of 20 randomly chosen plants per treatment were measured (N = 240). Significant differences among species and among provenances were found for both variables,
C. fissilis and C. angustifolia being the species with the tallest but thinnest seedlings. Among the provenances, C. fissilis San Antonio and Guaraní had the highest
average heights of the trial (33.0 cm and 27.7 cm, respectively) and the lowest
diameters (5.5 mm on average), while C. balansae Río Seco and Ledesma (undifferentiated) exhibited the highest mean diameters, with 7.8 and 8.0 mm, respectively (Fig. 14.6).
The status of carbohydrate reserves is a physiological parameter useful to infer
vigor and health of a plant and might have an effect on its performance in the field
(Birchler et al. 1998). In turn, the adaptation of a species to low temperatures can be
evaluated by testing the resistance of its cell membranes to freezing. Such a test can
be performed indirectly by subjecting its fresh leaves to freezing, then immersing
them in deionized water, and finally measuring the electrical conductivity of the
solution formed by the water and solutes released by the leaves. The measured conductivity is a function of the breakage of the cell membranes by freezing (Dexter
et al. 1932; Rodríguez-Rey et al. 2000).
From the previous trial, seven seedlings per treatment were transplanted into
3000 cm
3
pots 70 days after germination and were grown for 1 year within a greenhouse. In autumn (temperatures between 10 °C and 15 °C), winter (& lt; 10 °C), and
J. Grignola et al.
The shoot height (Fig. 14.5b) of C. balansae Río Seco and C. fissilis Guaraní was
significantly affected under 600 mm with respect to the 1200 mm treatment. A different behavior was observed in C. balansae × C. saltensis hybrid (Pintascayo),
which was not affected by the water deficit, since it presented no significant differences between 600 mm and 1200 mm treatments.
The water balance was more efficient in seedlings from natural environments
with lower rainfall regimes. Besides, the efficiency was also manifested in the water
use, since the provenances from natural drier environments were able to grow more
when the water regime treatment was lower. Differences on drought responses
among tree ecotypes growing in tropical and subtropical rainforests may be attributed to genetic differences in physiological and morphological adaptive responses
(Engelbrecht and Kursar 2003). Plant responses to water deficit, when they are outside their natural environments, depend on the rainfall regimes of their native habitats (Otieno et al. 2005).
In a subsequent trial, all Argentinian species of the genus were compared with
respect to growth traits (Grignola 2014). It included five provenances of C. balansae, two of C. fissilis, two of the hybrids between C. saltensis and C. balansae, two
of C. saltensis, and, since it was not possible to obtain enough seeds of C. angustifolia from the same provenance, a pool of several sources was used to represent this
species. The trial was established on 100 cm
3
individual pots filled with inert substrate and slow-release fertilizer in the greenhouse of Famaillá Experimental Station
(27° 3’ S, 65° 25’ W, 450 m asl), with seeds from trees selected in the natural forest
according to growth, health, and shape criteria. The hybrid character of adult plants
of C. saltensis × C. balansae was confirmed through genetic markers.
Seventy days after germination, the total height and collar diameter of 20 randomly chosen plants per treatment were measured (N = 240). Significant differences among species and among provenances were found for both variables,
C. fissilis and C. angustifolia being the species with the tallest but thinnest seedlings. Among the provenances, C. fissilis San Antonio and Guaraní had the highest
average heights of the trial (33.0 cm and 27.7 cm, respectively) and the lowest
diameters (5.5 mm on average), while C. balansae Río Seco and Ledesma (undifferentiated) exhibited the highest mean diameters, with 7.8 and 8.0 mm, respectively (Fig. 14.6).
The status of carbohydrate reserves is a physiological parameter useful to infer
vigor and health of a plant and might have an effect on its performance in the field
(Birchler et al. 1998). In turn, the adaptation of a species to low temperatures can be
evaluated by testing the resistance of its cell membranes to freezing. Such a test can
be performed indirectly by subjecting its fresh leaves to freezing, then immersing
them in deionized water, and finally measuring the electrical conductivity of the
solution formed by the water and solutes released by the leaves. The measured conductivity is a function of the breakage of the cell membranes by freezing (Dexter
et al. 1932; Rodríguez-Rey et al. 2000).
From the previous trial, seven seedlings per treatment were transplanted into
3000 cm
3
pots 70 days after germination and were grown for 1 year within a greenhouse. In autumn (temperatures between 10 °C and 15 °C), winter (& lt; 10 °C), and
J. Grignola et al.